Preparation and Characterization of Citrate Sol-gel Derived CaLa_4Ti_4O_(15) Microwave Dielectric Ceramics

摘要

In this work hexagonal perovskite powders of CaLa_4Ti_4O_(15) were prepared by citrate sol-gel method. The calcined temperature was 1150°C, which is lower than that of the conventional solid method. Dense CLT ceramics were produced at sintering temperature of 1600°C. The crystal structures and microstructures were investigated by XRD, TEM and SEM, respectively. Compared with samples produced by solid method, the sol-gel derived CLT ceramics exhibited a near zero temperature coefficient of resonant frequency (τ_f) of-6 ppm/°C, and other microwave properties , ε_r～ 43, Q×f ～ 42000 GHz were also obtained. Moreover, the sintering temperature of the CLT ceramics could be reduced to 1400 °C by addition of B_2O_3-ZnO.